The Seaway pipeline, a 36-year-old oil and gas pipeline, is being “repurposed” to carry a poisonous mix of chemicals and tar sands bitumen up to 20 times more toxic than traditional crude. Unless we act, the poison blend will flow across Richland Chambers Lake and under tributaries leading to Lavon Lake — major water resources serving Dallas and Fort Worth — starting May 17.

Since a previous attempt by the same company, Enbridge Inc. of Canada, to repurpose a 43-year-old pipeline in Michigan resulted in one of the most expensive pipeline spills in U.S. history — a spill that still hasn’t been cleaned up after 20 months — residents have every reason to be troubled about what may be flowing through Seaway soon.

Tar sands are often described as a dirtier form of crude oil and are more like asphalt than petroleum. It is mined, not drilled and pumped like oil. It is solid at ambient temperatures and far more acidic than crude oil.

To push tar sands through a pipeline, chemical diluents must be added. Like some fracking companies, Enbridge and other pipeline operators have refused to disclose what’s in the diluents, saying that the toxic mix is proprietary. What we know, or learned from tar sands pipeline spills, is that the blend is heavy in benzene, a toxin hazardous at just 6 parts per billion, and many other chemicals that are far more deadly than anything in a traditional oil pipeline.

In other words, tar sands ain’t your grandaddy’s crude.

Even with these toxic diluents, tar sands bitumen is so thick and heavy that pipelines built for it typically operate at pressures above 1,200 psi. For comparison, a standard sweet crude pipeline will operate below 150 psi, and an oil pipeline is considered at high pressure at 500-600 psi.

The higher the pressure on the pipeline, the greater the risk of a spill and the more significant a spill is likely to be. One spill on the Keystone I pipeline shot tar sands six stories into the air. Enbridge has announced plans to “twin” an ultra-high-pressure line alongside the aging Seaway line that could have similar problems.

But Enbridge already has a far more impressive tar sands spill on its record. The company repurposed the 43-year-old Line 6B to carry tar sands across Michigan. Operating below the pressure allowed under the Seaway permit, Line 6B ruptured and poured more than 1 million gallons of the tar sands blend into the Kalamazoo River in July 2010.

To date, the Enbridge spill on the Kalamazoo is one of the most expensive pipeline spills in U.S. history.

One reason it has been so expensive is that tar sands bitumen is heavier than oil and sinks in water. This makes cleanup almost impossible, so it’s little wonder that the Kalamazoo cleanup has exceeded $700 million (and climbing). A large section of the river is still off limits, and now the company faces a whistle-blower lawsuit from a worker with evidence that Enbridge was covering up the spill instead of cleaning it.

Texas water supplies are too precious and limited to risk these kinds of accidents. Seaway also crosses the Trinity and Carrizo Wilcox aquifers, passing through seven counties in D-FW’s regional water planning district.

Both the EPA and the Pipeline and Hazardous Materials Safety Administration have roles to play and should act quickly to evaluate Seaway’s safety. But they won’t — unless you tell them to. It’s critical that an Environmental Impact Statement be done for this pipeline. Remember:

This is a pipeline of poison that was never designed to handle heavy tar sands bitumen.

The risk to Texas water supplies is too high and cleanup is virtually impossible.

Seaway won’t create any new jobs, and the project’s announcement has already raised the price of oil

Texans are renowned for fighting over water. With a pipeline of poison threatening Lavon Lake and Richland Chambers, now is a good time to live up to that reputation.

Tom “Smitty” Smith is director and Trevor Lovell the environmental program coordinator of Public Citizen’s Texas office. They may be contacted through tlovell@citizen.org.

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